CN110702485A - Device and method for testing influence of cement water separation on sand layer permeation grouting effect - Google Patents
Device and method for testing influence of cement water separation on sand layer permeation grouting effect Download PDFInfo
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- 239000004576 sand Substances 0.000 title claims abstract description 76
- 239000004568 cement Substances 0.000 title claims abstract description 72
- 238000012360 testing method Methods 0.000 title claims abstract description 69
- 230000000694 effects Effects 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 46
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 39
- 238000000926 separation method Methods 0.000 title claims description 30
- 239000002002 slurry Substances 0.000 claims abstract description 81
- 239000002245 particle Substances 0.000 claims abstract description 29
- 230000002787 reinforcement Effects 0.000 claims abstract description 29
- 238000003860 storage Methods 0.000 claims abstract description 20
- 238000009826 distribution Methods 0.000 claims abstract description 13
- 239000011440 grout Substances 0.000 claims description 28
- 230000008569 process Effects 0.000 claims description 22
- 239000003638 chemical reducing agent Substances 0.000 claims description 16
- 238000007569 slipcasting Methods 0.000 claims description 14
- 238000005520 cutting process Methods 0.000 claims description 12
- 230000035699 permeability Effects 0.000 claims description 11
- 230000003014 reinforcing effect Effects 0.000 claims description 11
- 230000008595 infiltration Effects 0.000 claims description 8
- 238000001764 infiltration Methods 0.000 claims description 8
- 230000000740 bleeding effect Effects 0.000 claims description 7
- 238000013461 design Methods 0.000 claims description 6
- 239000011148 porous material Substances 0.000 claims description 6
- 238000005056 compaction Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 239000000945 filler Substances 0.000 claims 1
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- 230000003204 osmotic effect Effects 0.000 claims 1
- 238000007873 sieving Methods 0.000 claims 1
- 230000009471 action Effects 0.000 abstract description 8
- 238000012113 quantitative test Methods 0.000 abstract description 6
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/366—Moulds; Demoulding
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
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- G01N2203/0252—Monoaxial, i.e. the forces being applied along a single axis of the specimen
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
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Abstract
The invention discloses a device and a method for testing the influence of cement precipitation on the seepage grouting effect of a sand layer, wherein the device comprises a pressure supply and slurry discharge device, a test bed and a grouting pipe, grouting pressure is provided by the pressure supply and slurry discharge device, cement slurry is stored in a slurry storage box, flows through a high-pressure-resistant hose under the action of a grouting pump and finally enters sand particles in the grouting pipe, and accordingly the seepage grouting of the sand layer is realized. And after grouting is finished, maintaining for a plurality of times under the same conditions, then removing the mold to measure various performance parameters of the grouting reinforcement body at different height positions, and finally realizing quantitative test of spatial distribution nonuniformity of the sand layer permeation grouting effect.
Description
Technical Field
The invention relates to a device and a method, in particular to a device and a method for testing the influence of cement water separation on the sand layer permeation grouting effect.
Background
The inventor finds that when underground engineering is built in stratums with good pore connectivity such as a pebble layer, a coarse and medium sand layer and the like, permeable grouting is the most common method for reinforcing the stratums, meanwhile, cement grout is the most common grouting material at present, the cement grout is widely applied in grouting engineering, but the cement grout has a water bleeding effect, and the water bleeding and the cement particle settlement can cause the nonuniformity of the cement grout in space distribution, so that the lower reinforcing effect of a grouting reinforcing body is good, the upper reinforcing effect is poor, the grouting effect is large in spatial difference, the nonuniformity of the grouting reinforcing effect of the sand layer can have a non-negligible influence on the stability of the project to be reinforced, however, the water bleeding effect of the cement grout cannot be considered in the current grouting design, and a device and a method for quantitatively testing the nonuniformity are not available.
Disclosure of Invention
The invention aims to overcome the defects of the conventional device and method and provides a device and a method for testing the influence of cement water separation on the sand layer permeation grouting effect. The device simulates the seepage grouting process of cement grout in a sand layer, realizes the simulation of the water separation effect of the cement grout, and realizes the quantitative test of the spatial distribution nonuniformity of the grouting reinforcement effect of the sand layer by measuring various performance parameters of grout stone bodies at different positions after grouting.
In order to achieve the purpose, the device adopts the following technical scheme.
In a first aspect, the invention provides a device for testing the influence of cement water separation on the seepage grouting effect of a sand layer, which comprises a pressure and slurry supply and discharge device, a test bed and a grouting pipe, wherein the pressure and slurry supply and discharge device is connected with the test bed;
the grouting pipes comprise a plurality of grouting pipes which are fixed on the test bed and provided with grouting pressure for each grouting pipe by the pressure and slurry outlet device;
each grouting pipe comprises a pipe cap, a PVC pipe, a reducer union and a valve, the upper end of the PVC pipe is connected with the pipe cap, air holes are formed in the pipe cap to ensure that gas in the pipe is fully discharged in the process of seepage grouting, a fine wire netting is laid in the pipe cap, and the diameter of the wire netting is not more than that of sand particles; the lower end of the PVC pipe is connected with the reducer union, a valve is arranged below the reducer union, and the grouting pipe is always kept vertical on the test bed, so that the water bleeding direction of cement slurry is consistent with the axial direction of the grouting pipe;
the pressure supply and slurry discharge device comprises a grouting pump and a slurry storage box, grouting pressure is provided by the grouting pump in a test, cement slurry is stored in the slurry storage box, the grouting pump provides air pressure to enable the slurry to flow through a grouting pipeline from the slurry storage box and to be injected into a sand layer, and a grouting pipe is kept vertical in the grouting process, so that the permeation grouting of the sand layer is realized; and after grouting is finished, maintaining under the same condition, then removing the mold to measure various performance parameters of the grouting reinforcement body at different positions, and finally obtaining the influence of cement slurry water separation on the spatial distribution nonuniformity of the permeation grouting effect.
Further, the conditions that the grouting pressure and the grouting rate of the pressure supply and grouting device meet are as follows: the pore structure of the sand layer is not disturbed in the process of penetrating and grouting, and the grouting pipe can be prevented from being broken due to high pressure.
Furthermore, the slurry storage box adopts a semi-open type slurry storage box, so that the grouting and the stirring of the cement slurry are facilitated, and the influence on the uniformity of the slurry caused by the water separation effect generated by the gravity action during the standing of the slurry in the grouting process is avoided.
Furthermore, the test bed is formed by welding steel pipes. Every side of slip casting pipe fixed bolster all sets up a plurality of slip casting pipe fixed orificess, can once only place many slip casting pipes, can realize large batch developing test, improves test efficiency, reduces experimental error.
Furthermore, the length of the grouting pipe is 1.5-2m, so that cement slurry can be fully separated out, and a sufficient number of test blocks can be ensured when the grouting pipe is subjected to sectional sampling after grouting.
Furthermore, the reducing joint comprises a lower part, a connecting part and an upper part, wherein the lower part is cylindrical, the upper part is cylindrical, the connecting part is conical, the upper part and the lower part are connected through the connecting part to form a whole, and the radius of the lower part is smaller than that of the upper part; adopt reducing joint to prevent that the sand bed from flowing into the valve from the PVC pipe under the action of gravity, reduce the influence of hourglass sand to the experiment, effectively reduce the detention regional volume of pure cement simultaneously, reduce its influence to the process of bleeding.
Furthermore, a fine and dense wire mesh is laid at the reducing joint, so that the injected medium is further fixed, the cement slurry is filtered, and impurities are prevented from entering the grouting pipe to influence the grouting reinforcement effect.
Furthermore, a fine wire mesh is laid in the pipe cap, the diameter of a mesh of the wire mesh is not more than that of the sand particles, slurry is allowed to enter and exit, but the sand particles are not allowed to pass through so as to fix a poured medium, and the sand particles are prevented from moving integrally due to grouting diffusion in the grouting process.
In a second aspect, the invention also provides a method for testing the influence of cement slurry water separation on the sand layer permeation grouting effect, which comprises the following steps:
the method comprises the following steps: and (4) filling. Closing a valve at the lower side of the grouting pipe, controlling the grain size grading of sand particles in a sand layer by a screening method, controlling the compactness of the sand layer by the quality of the filled sand particles, filling the selected sand particles into the grouting pipe in layers according to the test design and compacting the selected sand particles in layers, controlling the compaction times and the compaction force and ensuring that the sand particles are fully distributed in the whole grouting pipe space.
Step two: assembling the test model and connecting the pipeline. The pipe cap, the reducer union and the valve are bonded on the grouting pipe, the grouting pipe is fixed on the test bench, the grouting pipe is kept vertical, the lower end of the grouting pipe is connected with the high-pressure-resistant hose, and the other side of the high-pressure-resistant hose is connected with the pressure-supplying slurry outlet device.
Step three: and (5) carrying out a grouting test. And opening a valve at the lower side of the grouting pipe, arranging cement slurry with a corresponding water-cement ratio in a slurry storage box according to test design, injecting the cement slurry into the grouting pipe at a low speed by using a grouting pump until a pipe cap at the upper side of the grouting pipe emits slurry, and finishing grouting. In order to avoid the influence of water precipitation of cement slurry on the uniformity of the slurry in the grouting process, the slurry is stirred and grouted.
Step four: and (5) maintaining and removing the mold. After grouting, all grouting pipes are placed in a curing chamber, and after curing reaches a specified condition, demolding is carried out, (the specific curing condition is 20 ℃, the humidity is more than 95%, and demolding is carried out after curing is carried out for 7 days, 14 days and 28 days respectively). And marking cutting lines at intervals of 10cm from the bottom of the grouting pipe during mold stripping, sequentially cutting off the cutting lines to ensure that the surface of the sample is smooth and flat, vertically cutting off the grouting pipe along the direction vertical to the cross section at the outer edge of the cut-off grouting pipe, taking out the grouting reinforcement bodies, and recording the distance between each section of grouting reinforcement body and the bottom by using a label and numbering the grouting reinforcement bodies.
Step five: and (6) measuring the grouting effect. Measuring the uniaxial compressive strength of the grouting reinforcement test piece by using a universal testing machine, and calculating according to a corresponding stress-strain curve to obtain a deformation modulus; and measuring the permeability coefficient by using a permeability coefficient measuring instrument, and representing the grouting effect by the uniaxial compressive strength, the deformation modulus and the permeability coefficient of the grouting reinforcement body.
Step six: and processing test data, and drawing a change curve of the reinforcing effect indexes (uniaxial compressive strength, deformation modulus and permeability coefficient) along with the height of the space at the bottom of the grouting pipe.
The invention discloses a device and a method for testing the influence of cement grout water separation on the sand layer permeation grouting effect, which realize the quantitative test of the water separation effect on the nonuniformity of the performance space distribution of a grouting reinforcement body.
The invention has the following advantages:
1. the device integrally realizes the quantitative test of the spatial distribution nonuniformity of the performance of the permeable grouting reinforcement body of the sand layer by the liquid water separation effect of the cement paste;
2. the grouting device can realize that the pore structure of a sand layer is not disturbed in the process of permeation grouting, and can prevent the grouting pipe from being broken due to high pressure; the device adopts the semi-open type slurry storage tank, so that the cement slurry can be conveniently stirred while grouting, the problem that the uniformity of the slurry is influenced due to the water separation effect generated by the gravity action when the slurry is kept still in the grouting process is avoided, the cement slurry is prevented from generating water separation in advance, and the slurry is homogeneous in the grouting process;
3. and fine wire netting is laid in the pipe cap, the diameter of meshes of the wire netting is not more than that of sand particles, slurry is allowed to enter and exit, but the sand particles are not allowed to pass through to fix a poured medium, and the sand particles are prevented from moving integrally due to grouting diffusion in the grouting process.
4. The test bed is formed by welding steel pipes. Every side of slip casting pipe fixed bolster all sets up a plurality of slip casting pipe fixed orificess, can once only place many slip casting pipes, can realize large batch developing the experiment, improves test efficiency, reduces experimental error.
5. The reducing joint is adopted to prevent a sand layer from flowing into the valve from the PVC pipe under the action of gravity, so that the influence of sand leakage on a test is reduced, the volume of a detention area of pure cement is effectively reduced, and the influence of the detention area on a water separation process is reduced; and a fine wire mesh is laid at the reducing joint to further fix the injected medium and filter the cement slurry, so that impurities are prevented from entering the grouting pipe to influence the grouting reinforcement effect.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention and are not intended to constitute an admission of the invention.
FIG. 1 is a schematic diagram of an overall framework of a grouting system;
FIGS. 2(a) and 2(b) are schematic cross-sectional views of a reducer union and a pipe cap;
FIG. 3 is a schematic longitudinal section and cut-away view of a grout pipe;
fig. 4 is a schematic view of a method for removing the grouting reinforcement body.
The spacing or dimensions between each other are exaggerated to show the location of the various parts, and the illustration is for illustrative purposes only. In the figure: 1-a device for pressing and discharging pulp; 2- -slurry storage tank; 3- -cement grout; 4- -high compression hose; 5- -the valve; 6-a reducer union; 7- -grouting pipe; 8-pipe cap; 9- -sand particles; 10- -test rig; 11- -grouting pipe fixing support; 12-grouting reinforcement; 13- -a cutting line; 14- -demolding the test specimen; 15- -the tube wall; 16- -wire netting; 17- -air holes; 18- -grout inlet; 19-grouting pump.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
as introduced in the background art, when the underground engineering is built in the stratum with good pore connectivity, such as the gravel layer, the coarse and medium sand layer, etc., the infiltration grouting is the most common method for reinforcing the stratum, meanwhile, the cement grout is the most common grouting material at present, the cement grout is widely applied in the grouting engineering, but the cement grout has a water precipitation effect, and the precipitation of water and the sedimentation of cement particles can cause the nonuniformity of the cement grout in space distribution, so that the reinforcing effect of the lower part of the grouting reinforcement body is good, the upper part of the grouting reinforcement body is poor, the grouting effect is greatly different in space, the nonuniformity of the grouting reinforcement effect of the sand layer can have a non-negligible influence on the stability of the project to be reinforced, however, the current grouting design can not consider the water precipitation effect of the cement grout, and no device and method for quantitatively testing the difference exist, in order to solve the above technical problems, the application provides a device and a method for testing influence of cement water separation on sand layer permeation grouting effect.
In a typical embodiment of this application, as shown in fig. 1, the device for testing the influence of cement water separation on the effect of sand bed infiltration slip casting can realize the quantitative test of the cement water separation effect on the spatial distribution nonuniformity of the effect of sand bed infiltration slip casting reinforcement. The device comprises a pressure and slurry outlet device 1, a test bench 10 and a grouting pipe 7. The test provides grouting pressure through the pressure supply and discharge device 1, and cement grout 3 is stored in the grout storage tank 2 and flows through the high pressure resistant hose 4 through the action of the grouting pump 19, and finally is injected into the sand particles 9 in the grouting pipe 7, and the grouting pipe 7 is kept vertical in the test process.
The pressure-out slurry device 1 provides grouting pressure. The grouting device can realize low-pressure slow seepage, does not disturb the pore structure of a sand layer in the seepage grouting process, and can prevent the grouting pipe 7 from cracking due to high pressure; the device comprises a semi-open type slurry storage tank 2 and a grouting pump 19. The slurry storage tank 2 is in a semi-open type, so that the cement slurry 3 can be stirred while grouting is performed conveniently, and the problem that the uniformity of the slurry is influenced by a water separation effect generated by the gravity action when the slurry is kept stand in the grouting process is avoided. The slurry storage tank 2 is connected with the grouting pipe 7 through a grouting pump 19 and a high pressure-resistant hose 4.
The test bed 10 is formed by welding steel pipes, each side of the grouting pipe fixing support 11 is provided with a plurality of fixing holes, and a plurality of grouting pipes 7 can be placed at one time; in this embodiment, each side of slip casting pipe fixed bolster 11 all sets up 10 fixed orificess, can once only place 20 slip casting pipes 7 at most, can realize large batch development experiment, improves test efficiency, reduces experimental error. In fig. 1, only 9 grouting pipes 7 are provided.
As shown in figure 3, every slip casting pipe 7 includes pipe cap 8, PVC pipe, reducer union 6, valve 5, and pipe cap 8 is installed in PVC pipe upper end, and reducer union 6 is installed at PVC pipe lower extreme, installs valve 5 under the reducer union 6, and the slip casting pipe 7 remains throughout vertical in the test process, and slip casting pipe 7 is long 1.5 ~ 2 m. Specifically, the specific connection mode among the pipe cap 8, the PVC pipe, the reducer union 6 and the valve 5 can adopt bonding, welding, threaded connection and the like, and can be selected according to actual needs.
The grouting pipe 7 is kept vertical all the time, the water bleeding direction of the cement slurry 3 is consistent with the axial direction of the grouting pipe 7, meanwhile, the grouting pipe 7 is 1.5-2m long, the cement slurry 3 can fully bleed, and after grouting, sufficient test blocks can be guaranteed when segmented sampling of the grouting pipe 7 is carried out.
The pipe cap 8 is provided with the air vent 17 to ensure that gas in the pipe is fully discharged in the process of permeation grouting, and when the pipe cap 8 starts to emit grout, the cement grout 3 in the PVC pipe is full, and grouting is finished. Further, as shown in fig. 2(a), a fine wire mesh 16 is laid in the pipe cap 8, the diameter of the wire mesh is not more than that of the sand particles 9, slurry is allowed to enter and exit, but the sand particles 9 are not allowed to pass through so as to fix the injected medium, and the sand particles 9 are prevented from moving integrally due to grouting diffusion in the grouting process;
in the embodiment, the reducing joint 6 is adopted to prevent a sand layer from flowing into the valve 5 from the PVC pipe under the action of gravity, so that the influence of sand leakage on the test is reduced, the volume of a detention area of pure cement is effectively reduced, and the influence of the detention area on a water separation process is reduced; the reducing joint 6 has the specific structure that the inner diameter of the bottom is smaller than that of the upper part, and comprises a lower part, a connecting part and an upper part, wherein the lower part is cylindrical, the upper part is cylindrical, the connecting part is conical, the upper part and the lower part are connected through the connecting part to form a whole, and the radius of the lower part is smaller than that of the upper part. And a fine wire mesh 16 is laid at the position of the reducer union 6, as shown in fig. 2(b), and the purpose is to further fix the injected medium and filter the cement slurry 3 at the same time, so that impurities are prevented from entering the grouting pipe 7 to influence the grouting reinforcement effect.
Furthermore, the valve 5 adopts the existing valve structure, and the valve 5 is connected with the pressure-supply slurry outlet device 1 through the high pressure-resistant hose 4.
The device simulates the seepage grouting process of cement grout in a sand layer, realizes the simulation of the water separation effect of the cement grout, and realizes the quantitative test of the spatial distribution nonuniformity of the grouting reinforcement effect of the sand layer by measuring various performance parameters of grout stone bodies at different positions after grouting. The grouting pump is used for providing grouting pressure during the test, cement slurry is stored in the slurry storage box, the grouting pump is used for providing air pressure to enable the slurry to flow through a grouting pipeline from the slurry storage box and to be injected into a sand layer, and a grouting pipe is kept vertical during the grouting process, so that the permeable grouting of the sand layer is realized. And after grouting is finished, maintaining for a plurality of times under the same conditions, then removing the mold to measure various performance parameters of the grouting reinforcement body at different positions, and finally obtaining the influence of cement slurry water separation on the spatial distribution nonuniformity of the permeation grouting effect.
Further, the following describes the specific implementation method of the present invention with reference to the drawings and examples.
The grouting material adopts cement slurry with W: C being 1.0, the injected medium is medium sand (the particle size range is 2.5-5 mm), and the experimental steps are as follows:
the method comprises the following steps: and (4) filling. Closing the valve 5 at the lower side of the grouting pipe 7, filling the selected sand particles into the permeation grouting pipe 7 layer by layer and compacting layer by layer, controlling the compacting times and compacting force, and ensuring that the sand particles 9 are fully distributed in the whole space of the grouting pipe 7.
Step two: assembling the test model and connecting the pipeline.
The pipe cap 8, the reducing joint 6 and the valve 5 are connected to the grouting pipe 7, the grouting pipe 7 is fixed on the test bed 10, the vertical state is kept, the lower end of the grouting pipe 7 is connected with the high pressure-resistant hose 4, and the other side of the high pressure-resistant hose 4 is connected with the pressure-supply slurry outlet device 1.
Wherein, the pipe cap 8 is processed with the air vent 17 in advance, and the wire netting 16 is placed in advance inside; the wire netting 16 is also fixed in the reducing joint 6 in advance;
step three: and (5) carrying out a grouting test. And opening a valve 5 at the lower side of the grouting pipe 7, pouring cement slurry 3 with the preset W: C being 1.0 into the slurry storage tank 2, and injecting the cement slurry 3 into the grouting pipe 7 at a low speed by using an injection pump 19 until the pipe cap 8 at the upper side of the grouting pipe 7 discharges slurry, thus finishing grouting.
Step four: and (5) maintaining and removing the mold. After grouting, all grouting pipes 7 are placed in a curing chamber, curing is carried out for 7 days, 14 days and 28 days under the condition that the temperature is 20 ℃ and the humidity is more than 95%, and then the mold is removed. Marking cutting lines 13 at intervals of 10cm from the bottom of the grouting pipe 7 during mold stripping, sequentially cutting off the cutting lines, vertically cutting off the grouting pipe 7 along the direction vertical to the cross section at the outer edge of each section of the grouting pipe 7, taking out the grouting reinforcement body 12, and recording the distance between each section of the grouting reinforcement body 12 and the bottom by using a label and numbering; as shown in detail in fig. 4.
Step five: and (6) measuring the grouting effect. Measuring the uniaxial compressive strength of the grouting reinforcement test piece by using a universal testing machine, and calculating according to a stress-strain curve to obtain a deformation modulus; and measuring the permeability coefficient by using a permeability coefficient measuring instrument. The grouting effect is characterized by the uniaxial compressive strength, the deformation modulus and the permeability coefficient of the grouting reinforcement body 12.
Step six: and processing test data, and drawing reinforcing effect indexes, namely uniaxial compressive strength, deformation modulus and permeability coefficient, along with a change curve of the height of the bottom space of the grouting pipe 7.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. The device for testing the influence of the cement water separation on the sand layer permeation grouting effect is characterized by comprising a pressure supply and slurry outlet device, a test bed and a grouting pipe;
the grouting pipes comprise a plurality of grouting pipes which are fixed on the test bed and provided with grouting pressure for each grouting pipe by the pressure and slurry outlet device;
each grouting pipe comprises a pipe cap, a PVC pipe, a reducer union and a valve, wherein the upper end of the PVC pipe is connected with the pipe cap, air holes are formed in the pipe cap, a fine wire netting is laid in the pipe cap, and the diameter of the wire netting is not more than that of sand particles; the lower end of the PVC pipe is connected with the reducer union, a valve is arranged below the reducer union, and the grouting pipe is always kept vertical on the test bed, so that the water bleeding direction of cement slurry is consistent with the axial direction of the grouting pipe;
the pressure supply and slurry discharge device comprises a grouting pump and a slurry storage box, grouting pressure is provided by the grouting pump in a test, cement slurry is stored in the slurry storage box, the grouting pump provides air pressure to enable the slurry to flow through a grouting pipeline from the slurry storage box and to be injected into a sand layer, and a grouting pipe is kept vertical in the grouting process, so that the permeation grouting of the sand layer is realized; and after grouting is finished, maintaining under the same condition, then removing the mold to measure various performance parameters of the grouting reinforcement body at different positions, and finally obtaining the influence of cement slurry water separation on the spatial distribution nonuniformity of the permeation grouting effect.
2. The device for testing the influence of the cement water separation on the sand infiltration grouting effect as claimed in claim 1, wherein the grouting pressure and the grouting rate of the pressure and slurry output device meet the following conditions: the pore structure of the sand layer is not disturbed in the process of penetrating and grouting, and the grouting pipe can be prevented from being broken due to high pressure.
3. The apparatus for testing the effect of cement separation on the effect of osmotic grouting in a sand layer according to claim 1, wherein the grout box is a semi-open type grout box.
4. The device for testing the influence of the cement water separation on the sand infiltration grouting effect as claimed in claim 1, wherein the length of the grouting pipe is 1.5-2 m.
5. The apparatus for testing the effect of cement water separation on sand infiltration grouting according to claim 1, wherein the reducer union comprises a lower portion, a connecting portion and an upper portion, wherein the lower portion is cylindrical, the upper portion is cylindrical, the connecting portion is conical, the upper portion and the lower portion are connected through the connecting portion to form a whole, and the radius of the lower portion is smaller than that of the upper portion.
6. The apparatus for testing the effect of cement water separation on sand infiltration grouting according to claim 1, wherein a fine wire mesh is laid at the reducer union.
7. The method for testing the influence of the cement grout water separation on the sand layer permeation grouting effect by using the device of any one of claims 1 to 6 is characterized by comprising the following steps:
the method comprises the following steps: filler material
Filling the selected sand particles into the grouting pipe according to the test design, and controlling the compaction frequency and the compaction force to ensure that the sand particles are fully distributed in the whole grouting pipe space;
step two: assembling a test model and connecting a pipeline;
mounting a pipe cap, a reducing joint and a valve on a grouting pipe, wherein the grouting pipe is fixed on a test bed, the lower end of the grouting pipe is connected with a high-pressure-resistant hose, and the other side of the high-pressure-resistant hose is connected with a pressure supply and slurry outlet device;
step three: carry out grouting test
Opening a valve at the lower side of the grouting pipe, configuring cement slurry with a corresponding water-cement ratio according to test design, placing the cement slurry in a slurry storage box, and injecting the cement slurry into the grouting pipe at a low speed by using a grouting pump;
step four: maintenance and form removal
After grouting, placing all grouting pipes in a curing chamber, curing for 7 days, 14 days and 28 days respectively under the condition of 20 ℃ and the humidity of more than 95 percent, and then removing the mold;
step five: measuring grouting effect
Measuring the uniaxial compressive strength of the grouting reinforcement test piece by using a universal testing machine, and calculating according to a stress-strain curve to obtain a deformation modulus; measuring the permeability coefficient by using a permeability coefficient measuring instrument;
step six: and processing test data, drawing reinforcing effect indexes, namely change curves of uniaxial compressive strength, deformation modulus and permeability coefficient along with the height of the space at the bottom of the grouting pipe, and quantitatively obtaining the spatial distribution nonuniformity of the grouting reinforcing effect.
8. The method of claim 7, wherein the size distribution of sand particles in the sand layer is controlled by sieving, the compactness of the sand layer is controlled by the quality of the packed sand particles, and the sand particles are packed in layers in the infiltration slip casting pipe and compacted in layers.
9. The method of claim 7, wherein the grouting is performed while stirring, and the grouting pipe is kept vertical during grouting; when the pipe cap bleeds out, the cement grout in the pipe is full, and grouting is finished.
10. The method of claim 7, wherein the mold is removed by marking cutting lines at intervals of 10cm from the bottom end of the grouting pipe and sequentially cutting the cutting lines, the surface of the sample is smooth and flat, the grouting pipe is vertically cut at the outer edge of the cut grouting pipe in a direction perpendicular to the cross section, the grouting reinforcement is taken out, and the distance from each section of the grouting reinforcement to the bottom of the grouting pipe is recorded by a label and numbered.
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CN112417547A (en) * | 2020-10-21 | 2021-02-26 | 山东大学 | Multi-scale and multi-field evolution simulation method and system for coastal sand layer grouting reinforcement strength |
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Publication number | Priority date | Publication date | Assignee | Title |
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CN112417547A (en) * | 2020-10-21 | 2021-02-26 | 山东大学 | Multi-scale and multi-field evolution simulation method and system for coastal sand layer grouting reinforcement strength |
CN112417547B (en) * | 2020-10-21 | 2023-06-30 | 山东大学 | Coastal sand layer grouting reinforcement strength multi-scale multi-field evolution simulation method and system |
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